1. Field of the Invention
This invention relates to an improvement in a tape clamp for fixing an end of a magnetic recording tape to a hub of a magnetic tape magazine.
2. Description of the Prior Art
In a magnetic tape magazine, the ends of a magnetic recording tape are fixed to take-up and feed-out hubs by means of a tape clamp. Generally the tape clamp is resiliently press-fitted into a recess provided in the outer surface of the hub and an end of the magnetic recording tape is clamped between the hub and the tape clamp. Conventionally, the tape clamp comprises a body portion having an outer surface and a pair of lugs projecting from the inner surface of the body portion at its ends. Each lug is provided with an outwardly extending shoulder for engagement with a shoulder formed on the wall of the recess when the tape clamp is press-fitted into the recess, thereby holding the tape clamp within the recess. The tape clamp is designed so that the outer surface of the body portion is inherently flat and is bowed to have a curvature equal to that of the outer peripheral surface of the hub and merging thereinto when the tape clamp is press-fitted into the recess of the hub.
However, a body portion having a flat outer surface cannot easily assume a bowed shape wherein the outer surface has a curvature precisely equal to that of the peripheral surface of the hub.
If the curvature of the outer surface of the body portion differs from that of the peripheral surface of the hub, when the tape clamp is press-fitted into the recess of the hub, deviation from circularity of the tape-clamp-hub assembly is increased. The increased deviation from circularity of the assembly could give rise to physical strains in the magnetic recording tape wound therearound. Such physical strains in the magnetic recording tape could adversely affect the quality of reproduction. This is especially true in case of a high performance reproduction system. Although, the above problem may be partly solved by forming the body portion so that its outer surface is inherently curved, this approach would result in reduced tape clamping force since the tape clamping force of such a conventional tape clamp solely depends upon the resiliency or rebounding force of the body portion.
Further, in the conventional tape clamp, the lugs generally have a wall thickness substantially larger than that of the body portion. Therefore, as is well known in the art, a serious sink mark is apt to occur in the outer surface of the body portion when the tape clamp is formed by plastic injection molding. The sink mark also adversely aggravates the deviation from circularity of the tape-clamp-hub assembly.